A few things you should also consider: 1) if you have the older back plate / SMC version I think its a slightly better sounding one over the newer 2.5mm jack version, 2) you have 2.5 years of enjoyment with them and like a car they depreciate quickly since they are not rare, 3) have you seen all the problems many are having with the current version with cracked yokes and drivers failing? So while yours might be older it still has value and to some it might be worth more than the $220 for a new one. I also find your complaint about the lost in value to be unwarranted since prices usually goes down with most tech products over time due do advancements in manufacturing and improved technology.i bought the 400i two and a half year ago for 499$. at the beginning i used them a lot, but over time i listened more with the hd 650 and since i have a portable setup (since a half year) i barely use the 400i. Now i was thinking about selling them. To my suprise the official store of hifiman on ebay sells them for 219$..... wow. This is very nice for people who were considering buying them but never really pulled the trigger. But for me this means, that the 400i is the first and the last product i will ever buy from hifiman. the loss in value is over 50% (if they would be new!). How could i be able to sell a two and a half year old hp for let's say for 200$ when someone can have them new for 219. for comparison: the hd 650 has nearly the same price since three years. Don't get me wrong here. i think the 400i is a good headphone. but the pricing policy sucks imo.
This is just my opinion